The proposed study will involve investigation of the mechanism and kinetics of binding of drug substrates to cytochrome P-450 by means of ultraviolet visible light spectroscopy. The effects of agents found to alter both the extent of binding and rate of metabolism of drugs will be assessed in an attempt to discern the manner in which they work. The nature of hemoproteins induced by different substrates of the enzyme will be investigated after purification and attempts will be made to assess the differences between them. Cytochrome P1-450 and P-450 will be isolated by the detergent Emulgen 911 and combined with similarly isolated tPNH cytochrome c-reductase for comparison of substrate specificity; this latter will be determined by spectrophotometric and metabolic assays. Studies will continue on the mechanism whereby the mitochondria stimulate the mixed function oxidase of the microsomes. Studies are planned using various inhibitors of mitochondrial function to discern possible crossover points in the stimulatory action.